The present invention relates to a new and improved method of manufacturing a compound camshaft. The present invention also relates to a new and improved construction of a compound camshaft which is obtained by carrying out the aforementioned inventive method.
In its more particular aspects, the present invention specifically relates to a new and improved method of manufacturing a compound camshaft and which method includes the steps of placing journal or bearing elements and/or cam elements on a camshaft body or camshaft element and fixedly connecting or securing the journal or bearing elements and/or the cam elements with such camshaft body or camshaft element.
The most various methods are known for manufacturing camshafts. For example, camshafts may be cast in one piece. Also, the cam elements and the other elements of the compound camshaft and the camshaft body itself can be separately manufactured and subsequently interconnected, for example, by welding or bolting or by any other known appropriate connecting method. Furthermore, and in order to achieve savings in weight, the camshafts obtained by either one of the aforementioned methods are bored-out or drilled-out. Such multi-step procedures are currently in general use, however, they have been found to be very cost-intensive and time-consuming.
It is further known to the art that under the tribological or frictional conditions which prevail during operation of a cam or camshaft drive, chill-cast cams possess the highest wear resistance.
According to a method of manufacturing compound camshafts as known, for example, from German Patent Publication No. 2,922,509, the journal or bearing elements for a support tube which constitutes the camshaft body and the cam elements are separately manufactured and subsequently interconnected in a force-locking manner and/or in a form-locking manner. The journal or bearing elements and the cam elements are connected with the support tube primarily by employing a soldering or so-called out-shrinking operation. During such soldering or out-shrinking operation, the profile or contours of the support tube carrying the journal or bearing elements and the cam elements must be machined into the related sections of such support tube constituting the camshaft body. Apart from the fact that such measures or steps require a comparatively great amount of work, it is not entirely apparent from this suggested prior art manufacturing method in which manner the soldering operation is intended to be carried out.